Constant velocity drive means



March 25, 1958 e. c. MOLYNEUX gal-AL 2,827,777

' CONSTANT VELOCITY DRIVE MEANS Filed Oct. '4, 195a s Sheets-Sheet 1do/f/v 5620/5 M; Mar/war E. .3.

March 1958 s. c. MOLYNEUX EI'AL 2,827,777

CONSTANT VELOCITY DRIVE MEANS 3 Sheets-Sheet 2 Filed Oct. 4, 1956 March25, 1958 G. c. MOLYNEUX ET AL 2,327,777

CONSTANT VELOCITY DRIVE MEANS 3 Sheets-Sheet 3 Filed 001;. 4, 1956 byI/EN roe:

United rates Fatent CONSTANT VELQCITY DRIVE MEANS Grevor C. Molyneux,North Balwyn, Victoria, John B.

McMahon, Kew, Victoria, and John Blackler, Drummoyne, Sydney, New SouthWales, Australia, assignors to The Molyneux Helicopter CompanyProprietary Limited, Victoria, Australia, a company of AustraliaApplication October 4, 1956, Serial No. 614,021

4 Claims. (Cl. 64-21) This invention relates to constant velocity drivemeans and is concerned more particularly although not necessarilyexclusively with a constant velocity drive means for a helicopter rotor.

In helicopter construction it is desirable for travelling movementwithout the risk of setting up large hub stresses that the or each rotorshould be connected to its driving shaft by a universal coupling whichallows the rotor to tilt in any direction. For a considerable part ofthe time in which a helicopter rotor is operating the rotor is tilted sothat a line normal to it is inclined at an angle of up to severaldegrees to the drive shaft axis. Because of this inclination cyclicinertia forces are liable to be set up when known types of universalcouphngs are used and these forces may set up undesirable vibrations andare likely to cause fatigue failures in the rotor and transmissionsystem.

It is an object of this invention to provide an improved couplingsuitable for helicopter rotors and with this object in view a rotoraccording to one form of this invention may be characterised byemploying articulated driving arms.

More particularly driving means according to the present invention maycomprise a driving member fixed to a shaft and a driven memberconstrained to rotate about an axis which intersects the axis of theshaft and can itself rotate about the point of intersection, and togglemembers connected together by a universal joint connection, one togglemember being pivotally connected to the driving member and constrainedto remain in a plane extending through the axis of the shaft, and theother toggle member being pivotally connected to the driven member andconstrained to remain in a plane extending through the axis of rotationof the driven member, characterised in that the lengths of the togglemembers are equal, in that the radial distance of the pivoting centresof the toggles from their respective axes are equal and in that thedistances of the said pivoting centres measured from the point ofintersection of the axes along their respective axes are also equal.

Other objects and features of the invention will be evident from thefollowing description wherein reference is made to the accompanyingdrawings. In this description:

Figure 1 is a diagrammatic view in elevation illustrating the principleof a constant velocity drive,

Figure 2 is a view similar to Figure 1 illustrating a modification ofthe principle shown therein, which is more suitable for a helicopterrotor construcuon,

Figure 3 is a plan view of a practical construction of helicopter rotorbased on the diagrammatic construction shown in Figure 2,

Figure 4 is a view in elevation of the rotor shown in Figure 3 with partof the casing cut away,

Figure 5 is an enlarged view in vertical section of the rotor shown inFigures 3 and 4, on the plane 5-5 of Figure 6,

Figure 6 is a plan view, partly in section,

Figure 7 is a view in section on the plane 77 of Figure 6,

Figure 8 is a fragmentary plan view on the plane 8-8 of Figure 6, and

Figure 9 is a sectional plan view on the plane 9-9 of Figure 6.

Referring firstly to Figure 1 of the drawings there is illustratedtherein a principle for obtaining a constant velocity drive from a shaftto a member which is tiltable with respect to the shaft. The shaft 11has fixed to it a disc or plate 12 which intersects the shaft at thepoint A. A tiltable shaft 13 is connected to the shaft 11 so as to becapable of moving in any direction about their intersecting point 0, anda rotary member 14 is fixed at right angles to the shaft 13,intersecting it at the point C.

Two toggle members 15 and 16 are pivotally connected to the members 12and 14 respectively at B and D, in such a manner that they areconstrained to move in planes containing the axes of the shafts 11 and13 respectively, and the other ends of the toggle members are {connectedtogether at E by a ball and socket or other joint which permits relativepivoting movement in any direction. It can be shown quite readily thatif the distances 0A and 0C are made equal, and the distances AB and CDare also made equal (in other words if the radial and axial components,with respect to the shaft 11, of the centre of the pivot at B from thecentre of gyration at O are respectively equal to the radial and axialcomponents, with respect to the shaft 13, of the centre of the pivot atD from the centre of gyration of O), and furthermore if the lengths ofthe toggle members are equal so that BE=DE, then the arrangement iscompletely symmetrical and if the shaft 11 is turned at a uniform rateand the shaft 13 and rotary member 14 are constrained to rotate aboutthe axis of the shaft 13 their rotation will also be uniform. Duringsuch movement the toggle comprising the members 15 and 16 opens as thepoints B and D diverge from their proximate positions shown.

It will be evident that instead of providing the shaft 13 and the rotarymember 14 to give the correction location in space of the point D, therotary member may be in the same plane as its centre of gyration O and aprojection extending out of this plane may be provided to locate thepoint D. Thus in Figure l the line OF illustrates a suitable positionfor the rotary member and the line FD represents the projectionextending out of the plane of the rotary member.

Figure 2 illustrates a modification of the principle shown in Figure 1wherein the disc or plate 12 is mounted on the shaft 11, intersecting itat the point A which in this case is above the point 0. The tiltableshaft is dis.- pensed with and the rotary member 14 is mounted so thatit can gyrate about the point 0 which is in the plane of the rotarymember 14. A projection 17 extends out of the plane of the member 14from the point F away from the plate 12, and the point D is thus locatedin space in the same Way as if the tiltable shaft had extended from 0along the chain-dotted line to the point C and the rotary member hadbeen fixed at right angles to this shaft at this point. Two togglemembers 15 and 16 are pivotally connected to the members 12 and 17respec! tively, the pivots being such as to constrain the toggle membersto move in the planes containing the lines 0A and OC respectively, andthe toggle members are connected together at E by a universal joint. Asbefore, if the shaft 11 is rotated uniformly the member 14 will alsorotate uniformly provided that OA=OC=FD, AB=CD=OF, and BE=DE.

In practice it is desirable to employ the principle illus; trated inFigure 2, to use a plurality of pairs of toggle members at spacedintervals, and to support the rotary member from the shaft by a gimbalarrangement.

Patented Mar. 25, 1958-- 7 new 23- Eachalve irine ea rie V V en a n eadlqu nme 'T n eef ji-re i 1 i s r e a eembly i rreee a e i h ew es l rnnbe fema i 5 .t n -th radie nreie innit ,;er i -v m n qa l o h e rrar err proper working clearance. 1 V

r in Figures 4 to 9 comprises a shaft 18 having splines'19 near itsupper end and externally screw-threaded above the splines at 20. Theshaft is fitted with a driving member 21 comprising a sleeve 22, Whichfits over the shaft and three integral radially projecting arms'23spaced 'at 120 apart. The upper section of the sleeve 22 is providedwith splines 24 to mate with those on the shaft. A split locating ring25 islet into an annular recess the driving member 21 and this bears onthe'top of the splines 19 when the shaft is inserted from the bottom ofthe member 21. The member 21 andthe shaft 18"are held together by a nut26 screwed on the end of the shaft with a washer 2 7 interposed betweenthenut'and the membe; 21. I i

The sleeve 22 has a downwardly directed shoulder 28 against which anassembly of two tapered rollerTaXia-l and thrust bearings 29 and 36 anda spacing ring 311s held by a washer 32 and a nut 33 which ishCreWedontothe lower end of the sleeve, this end being screiv-threaded for thepurpose. The outer races of the bearings 29 amass are mounted and heldin a ring 34 which recessed to receive the bearings and has a'sphericalexterior surface except for two radial projections or spigots 35 whicha're iam t e l Opposite each the Ib eqt 3Z Yew! a y a ape d le b n t T"v 1 M w sh I an nut 5 rse e 'ert 3. 1 1 n the spigot. I:

The bea i 3 e upp ted in arpr rr at l haped e s' esi e mba n '9 whi h ilali' 3 9 anally separable halves held together by holt s' tliandl p,and justgives a clearance for the ringjfl. g" ring 39 is also providedwithrecesses to ihous e' t ther tapered roller bearings A2 whichlare d1metrically n Qppositeeach'other, and spaced at 90 'liarfngs 36. Thebearings A2 arefsupporteli on spigots' i43j'of twp trunnion blocks.44which. are fastened byflbjolts s", 1 nuts 46 to a torque ring 47; Thert'orque rin'g i li' which is an annular rmernber with three radialp'roiectiofn's A8 spaced at 120 apart isrthus free toturniiiau v aboutthe point O,inFi'gi1res.'5 and 7' onr-the' axis shaft 1 8,butis=preventedfrom moving bofiily' lnflany r cmm I r A e l Eachoftheradially rnemberlfiislshaped 50 having a hollow boss 51"n;which,ahort rod ifjis e hu'eeenu e ae J a 11 .i me i i h @Pla ai ing thecentral {radial l ne of the ar rn 23 shackle and the'axis of the sh a ft.13. :ThisfdistaL rid 54 of ea h d- 2 m pl rrahe a w thfiat ll t jai 5 Esha l S rand fla e i t eethe rt uaaa \IPP toggle b rraa se e le tbee fiz el m mb h nn re .e grexi e z h shaft 1 aadrte tl iee tt ia' lm e iprojections 4-8 The lshack les. are t thattheircentre 1: es the em eqiall ae release h distal s. e e th re l i le s and machined to pgovide a cndrical id eea thi ee ete t bearing pads 58 are provided rfee euitab rthearee ei constrained; so

. bal arrangement 1" centres of the spindles 42 and 5d and thepart-spherical 7 end 54. Referring to Figure 5, the points A and C arelocated at the intersection'of the axis of the shaft'18 with thehorizontal lines through B and D respectively, and the poiht F isldcated at the intersection 'of'the hori zontal line through 0 with theverticalline through 'D. The mechanisin'isarranged so; that therelationship previously d cussed with"reference'to Figure'Z holds, i. e.0A"=0C'' +FD;"AB2cD:OF; and BE -DE)" Hence when the shaft 18 is'rot'atedat a uniform rate the torque ring 47 will also turn at a uniform rateabout its own axis, i. e. Without'cy'c'lic'variatioiofspeed,irrespective of whether it is at right angles to the axis of the shaft18 or oblique to it. V

'The assembly of t e drivin membe 1 the t rque ring 47, th togg e memers, and t e mbal e ppe tr e all enclosed in a housing 59 which is ajttachepl tpithe torque ring bvvbnlts no 12 1 1 nut 5 .1 T es rbq e annuts als fas e th t rque r 1 4 tea sp der? havin radial arm 3 on which'ni eh ehane n sleeves :64 y rth oto h ades ;65 re ported- I e eeree 64ea yaun rfil o h ch IQQE 1m nuelqledii w onstr ined t erat abou a taxian a dn've ber comprising a torque ring supported on the shaft on agimbal a ranaem ntaad her b us eiaedr i t bou when an rvh ehin eeteflieaxiec lith ea in memb and whic 332 i s lf .p yo l ran ,diree o abo thepo nt o :viut lr e tien comprisin t g ,mem-

her neete to eth ye l n ie ea jo n ,Q e at ai og l me ber b i ta con esd t "th A n m be and, ee' etrem d selhatit m a iaewhl fh passe t ou r ieeet e .Qiill amivl'eree oin alw r m n em n .9m et i a i Q at tt n flb div n membeut r v-9 d e lerfit ai r i in pivotally connectedlto thestrained so that; s

e te n e' h 29ire atii l ft efir iie lxaembe fli en h Jo l e'lte sl ememzer being eq a the adial d ease 9 ,tl e ir v t a pfm nt iee et v q andthe ne fe theiri e ae. e et e rmee r th ren in ers ct on o the axes a nt eepeet r ar of h amemhe eft euhie 'fi erar eete la e hens e ua '2. Acoupling according to claim 1 having a plurality taairete ltae enenber ACe a qri n -lter la m twhe e t a m n ione r piv t lwit re ree t th u mbr n ;4. ,Arco upling for elifect ing a constant velocitv drive between adriving shaft and a helicopter rotor assembly while permitting sai dassernhlytotilt relative to lthe aiiis 7777 r. a e en ne fia 'i l t elS1 1 portedg on the, shaft nd constrained against other rn oveof theshaft, comprising a driving member fixed on the shaft, an inner ringsupported on bearings for rotation on said shaft but constrained againstbodily movement, two spigots extending ifrom the ring on opposite sidesthereof with their axes on a diameter of the inner ring, bearingsmounted on said spigots, a gimbal ring surrounding the inner ring andhousing the said bearings in diametrically opposed recesses, said gimbalring having other diametrically spaced recesses spaced at 90 from thefirst mentioned recesses and housing two other bearings, a torque ring,two trunnion blocks fastened to the torque ring and having spigots onwhich said two other bearings are mounted, a pivot pin mounted in thedriving member with its axis at right angles to a plane through the axisof the shaft, a second pivot pin mounted in the torque ring with itsaxis at right angles to a plane through the axis of the torque ring, thedistance of the first pivot pin from the axis of the shaft being equalto the distance of the second pivot pin from the axis of the torquering, and the distances of each pivot pin from the common geometriccentre of the inner ring and the gimbal ring being also equal a pair oftoggle members connected together by a ball and socket joint, saidtoggle members being mounted for pivoting movement on the respectivepivot pins whereby the medial lines of said toggle members passingthrough the centre of the ball and socket are constrained to remain inplanes containing the axis of the shaft and the axis of the torque ringrespectively, and the distances of each pivot pin from the centre of theball and socket joint are equal, and means connecting the torque ring tothe rotor assembly.

References Cited in the file of this patent UNITED STATES PATENTS125,880 Clemens Apr. 23, 1872 1,498,876 lngoldby June 24, 1924 1,853,171Nettenstrom Apr. 12, 1932 2,440,225 Pullin Apr. 20, 1948 2,475,293Pentecost et a1. July 5, 1949

